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The discharge of dye-containing wastewater has caused severe problems as dye is harmful and toxic to living things. Activated carbon adsorption is an efficient removal strategy to treat dye wastewa...

The conventional methods of magnetic activated carbon preparation involved multiple steps and often result in poor removal performance. This work was aimed to evaluate the physicochemical and adsorptive properties of magnetic activated carbons produced via single-step preparation using zinc chloride/ferric chloride activation for rhodamine B removal. The materials were characterized for proximate and elemental composition, textural characteristics, surface chemistry, and magnetic properties. The magnetic activated carbon endows a specific surface area of 1775 m2/g with 93.8% mesoporosity, featured an excellent rhodamine B (RB) adsorption at 371 mg/g. The magnetic activated carbons prepared by conventional magnetization methods and non-magnetic activated carbon were also employed for comparison. The adsorption of RB is an endothermic and spontaneous process. The activation energy of 24.1–28.9 kJ/mol indicates that the process is physisorption. The magnetic activated carbon exhibits a higher recovery of 93.7% for three consecutive cycles at regeneration condition of 68.3 °C for 1 h. The findings demonstrate the practical views of a facile preparation of magnetic activated carbon in simplifying the separation in a fast and cost-effective manner for wastewater treatment.

The present study was aimed to characterize the adsorptive properties of spent commercial activated carbon (SAC) and its regenerated derivatives (Pyro-RAC and CO2-RAC) for the decolourization of me...

Chitosan synthesized from the Pessu river crab shell was screened to coarse (CC, 600 µm), medium (MC, 300 µm) and fine (FC, 150 µm) aggregate for phenol removal. The aggregates were characterized f...

The growth of science and technology over the world has led to the establishment of various industries which has helped the industrial, technological, and agricultural development of many n...

This study was aimed at evaluating the isotherm of lead(II), manganese(II), and cadmium(II) adsorption in single and multimetal solutions using Nigerian bentonite. The natural and calcined clays were characterized for specific surface area, surface morphology, elemental composition, and cation exchange capacity (CEC). The adsorption data were analyzed and interpreted using isotherm models. The natural bentonite exhibits a specific surface area of 23.5 m2/g and a CEC value of 47.7 mEq/100 g and displays a higher adsorption capacity of all heavy metals in both single and multimetal solutions than the calcined bentonite. The removal of lead(II) by natural bentonite in single-component system is 0.0448 mmol/g. The order of selectivity is lead(II) > cadmium(II) > manganese(II). Result also shows that both clays demonstrate a preferable adsorption toward lead(II). Lead(II) adsorption is less affected by the presence of counter cations in multimetal solution. The adsorption of heavy metals onto Dijah-Mon...

In this work, the effect of extraction parameters on catechin extraction from betel nuts was studied. The supercritical carbon dioxide extraction parameters were pressure, temperature, and solvent flow rate while using average particle size of 177.5 μm and 5% (v/v) methanol as modifiers. Detection and quantification of catechin were achieved using HPLC analysis. The highest amount of extract and catechin concentration were 34.00 mg extract/g sample and 565.38 ppm of catechin obtained at 30 MPa, 70°C, and 4 mL/min. The results given by optimization tools suggest the same operating conditions with less than 3% difference.

Multicomponent adsorption of lead(II), cadmium(II) and manganese(II) by Nigerian Dijah-Monkin bentonite clay was investigated. The clay samples were characterized for elemental composition, cation exchange capacity and textural properties. Natural bentonite exhibits cation exchange capacity of 47.7 meq/100 g and specific surface area of 23.5 m2/g. Manganese(II) displays higher values of rate constant than lead(II) in multimetals adsorption. However, lead(II) is favorably adsorbed onto bentonite adsorbents at different concentrations studied. The multimetals adsorption onto bentonite clay samples is site selective and site specific. The pseudo-second-order kinetics model gave a better fit to the adsorption data, suggesting ion exchange and/or complex formation. The adsorption mechanism could be described by intraparticle diffusion with some restriction of metals diffusion due to film or boundary layer. Also, the multicomponent adsorption is endothermic and becomes more spontaneous as temperature in...

The aim of this study was the evaluation of the physicochemical characteristics of surface modified Dijah-Monkin bentonite clay. The clay was modified by calcination and treatment with hydrochloric acid. The natural and modified clays were characterized by x-ray fluorescence (XRF), Fourier transform infrared (FTIR), x-ray diffraction (XRD), electron dispersive x-ray (EDX), thermogravimetric analysis (TG), scanning electron microscopy (SEM), elemental composition, cation exchange capacity (CEC), Brunauer–Emmett–Teller (BET) specific surface area and methylene blue adsorption. The XRF displayed the presence of SiO2 and Al2O3 in the range of 61.6–65.6 wt% and 19.4–21.7 wt%, respectively. The FTIR spectra showed the existence of Al–OH, Al–O, Si–O, and Si–O–Si functional groups in all clay samples, confirming the presence of hydrated aluminosilicate in the clay. The BET surface area decreased from 23.5 to 17.1 m2/g after acid treatment, while the CEC of clay samples range between 40.7 and 20.2 mEq/100 ...

Zinc chloride (ZnCl2) is a well-known activating agent in the preparation of activated carbon, a material that is widely used in the treatment of wastewater. However, the use of ZnCl2 rendering the inevitable aquatic environmental issues due to the toxicity of metal cations. This paper highlights an overview on the latest development of metal chloride-activated carbon with special focus on the characteristics of activated carbon and the hazardous effects of metal chloride salts on human health and environment. The discussion is directed to shed some light on the feasible use of less hazardous metal chloride salts in the preparation of activated carbon.

Effluents from various industries release volatile organic compounds (VOCs) into the environment which causes serious environmental hazards. Coconut shell-based porous carbons were synthesized using chemical activation with potassium hydroxide (KOH) for adsorption of benzene and toluene. Central composite design of the response surface methodology was used in the optimization of the preparation conditions of the porous carbons. The effects of microwave power, irradiation time, and KOH impregnation ratio (IR) on benzene and toluene removal were investigated. The optimum condition was obtained at microwave power of 500 W; irradiation time 4 min; and 1.5 KOH IR, which resulted in 84 and 85% removal of benzene and toluene, respectively, at 95% yield of activated carbon (AC) from the char. Equilibrium data were fitted to Langmuir, Freundlich, and Temkin isotherms with all the models having R2 > 0.94. The equilibrium data were best fitted by Langmuir isotherm, with maximum adsorption capacity of 212 and...

This article discusses the application of mixed reverse micelles in downstream processing of antibiotics. Purification and recovery processes for antibiotics in downstream processing are major expenses, about 70% of the total cost of production, giving them a significant impact on manufacturing cost. Moreover, there are a number of challenges and difficulties in the separation process requirements for antibiotics, since the mixture is quite complex, with broth, hazardous solvents, by-products, intermediate material, and impurities; in addition, antibiotics are easy to denature. Therefore, the development of effective separation techniques is required to produce high-purity of biomaterials. The use of reverse micelles is thought to be among the most promising due to the process's high selectivity and efficiency. Most studies on reverse micelle extraction technology have been performed by using anionic surfactant sodium bis (2-ethyl-1-hexyl) sulfosuccinate (AOT). However, the activities of antibiotics hoste...

This work was aimed to evaluate the adsorptive nature of palm oil mill effluent sludge ash for methylene blue dye removal in aqueous solution. Two types of palm oil mill effluent sludge collected from different treatment ponds, i.e. anaerobic and biopolishing were burnt to ash, and treated with 5 M HCl. The treated and untreated adsorbents were characterized for surface area and morphology. Methylene blue dye adsorption was carried out in laboratory at room temperature, and the adsorption data were analyzed based on equilibrium isotherm and kinetic models. The surface area of ash-adsorbents was found to increase more than 12 times after HCl treatment. The highest surface area recorded was 218 m2/g. Equilibrium data of ash-adsorbents obeyed Langmuir isotherm to linear approximation suggesting the monolayer uptake of methylene blue dye. The highest maximum uptake of 50.7 mg/g methylene blue dye (50% removal) was demonstrated by HCl-treated biopolishing ash-adsorbent at initial concentration of 200 m...

The work was aimed to investigate the effect of heat treatment of manure-compost-based activated carbons on the adsorption of copper from aqueous solution. Activated carbons were characterized according to physical structures and surface functional groups. All equilibrium data of activated carbons formerly treated at different temperatures obeyed Langmuir model to linear approximation. Results showed that copper ions favorably adsorbed onto the mesopores at lower equilibrium concentrations and subsequently changed to the micropores at higher equilibrium concentrations. It was found that the increase in electron density upon heat treatment offered higher tendency for the uniform amount of protons to occupy the surface sites. Analysis of Scatchard plots suggested that the affinity driven by the mesopores toward copper ions was stronger than that of the micropores.

Considerable concerns have been raised over the presence of lead(II) in water bodies. In this work, the performance of heat-treated cattle-manure-compost-activated carbons were investigated to remove lead(II) from aqueous solution. Activated carbons were prepared by one-step ZnCl2 activation followed by heat treatment at different temperatures. They were characterized according to BET surface area, pore size distribution, elemental analysis, pHPZC and Boehm’s titration. It was found that the increase of treatment temperature resulted in a decrease in both the BET surface area as well as the concentration of phenolic groups. However, such decreases were compensated by an increase of lead(II) by more than three times to a value of 0.110 mmol/g, and this was also true for commercial F400-activated carbon. Lead(II) adsorption onto heat-treated activated carbons could be described by Langmuir isotherm with weaker interaction to active sites. Results also suggested that the increase in lead(II) uptake w...